In modern dentistry, materials are used in the repair of teeth which require the application of light, particularly blue light, and sometimes near ultraviolet light, to cure the material. Typically, a dentist uses a hand held light gun with a guide tube to direct the light to the area of the patient's teeth to which the light curable material has been applied. Common dental visible light activated resin systems are polymerized by blue light in the 470 nm range. To obtain proper curing, it is necessary that the light be applied to the material for a significant period of time, e.g., 30 seconds or more. To ensure that the light from the light gun is applied to the proper area, the dentist or hygienist generally must observe where the light is being applied during this time.
Prolonged or repeated exposure to ultraviolet or blue light can lead to cataracts. Overexposure to relatively short wavelength visible light (e.g., less than 500 nm) may contribute to premature aging of the cornea and to senile macular degeneration. To avoid potential eye problems, dentists and hygienists commonly use light filters attached to their glasses which filter out the shorter wavelengths, or various types of light shields which are available as attachments to the light gun or which may be held separately from the light gun.
Because of the increasing concerns with possible cross contamination between patients, dental equipment that is in contact with or proximate to a patient generally must be sterilized before it is used again with another patient or disposed of altogether. Light shields presently available which attach to the light gun are generally relatively expensive, and it is not economically feasible to dispose of these shields after use with one patient. Existing disposable light shields have typically not been as effective as the more permanent type of shields and not as convenient to use. In particular, disposable shields often are not easily placed on the light gun before use and easily removed after use by the dentist, especially where surgical gloves are used by the dentist or hygienist.